Conventional paging systems utilize terrestrial delivery systems to provide paging and short messages to and from user terminals. These messages may include the delivery of E-mail and other stored messages that are sent via the Internet. These systems are local in nature, or at best are national systems. The advent of Mobile Satellite Systems (MSS) allows an extension of these systems to a global delivery of paging and other messages. Prior satellite-based systems, such as one known as Iridium, require on-board satellite processing to deliver messages to users which are known to be in certain locations. In such systems a central database, or distributed databases, use the satellites to deliver the paging traffic.
However, these and similar systems are inefficient since the user may be indoors and blocked to the satellite, thus preventing the satellite from delivering the message. The user terminal may also be turned off, and unable to receive paging messages.
Also, in conventional paging systems a user cannot roam from one paging system to another, since the paging systems are typically so different as to render the pager from one system unable to operate in the other.